Various forms of capping heads are currently on the market for applying plastic and aluminum closures onto containers. Until recently, non-threaded closures were inserted onto the neck of a container and a capping head came down and formed the closure to the shape of the bottle's neck. With the advent of plastic closures, it became possible to mold the threads into the closure such that it was no longer necessary to form the closure on the container's neck. With prethreaded closures, it became customary to place the closure on the container's neck and then move the container into alignment with a capping head which would come down, contact the closure, and screw it onto the container. The closure would be tightened to a predetermined desired torque by a non-frictional magnetic clutch which was located between the chuck and the quill portion of the capping head. See U.S. Pat. Nos. 4,364,218 and 4,492,068, and U.S. Ser. No. 602,237, filed Apr. 19, 1984 and assigned to Aluminum Company of America. Such capping heads worked satisfactorily provided the prethreaded closure was initially placed squarely upon the container's neck. Problems would occur, however, when the closure was cocked or angled relative to the container's neck. In such situations, the threads on the screw closures were susceptible to cross-threading or the closures would not be tightened satisfactorily before the magnetic clutch disengaged.
Now a capping head has been invented which places a prethreaded closure squarely on a prethreaded container and tightens it down to a predetermined torque value.